1. Made from high quality silicone material, soft and non-tonic. 2. Certificated by kinds of certifications, like UL,ISO9001, SGS, ROHS etc. 3. Weared comfortably, no any discomfort or stimulation to ears. 4. Ageing resistance, stretch resistance and more durable than other materials. 5. Moistureproof and waterproof, effectively supress bacteria.